1. Field on the Invention
This invention relates to an automatic cassette changer which automatically exchanges various cassettes in which record media in the form of tapes or disks are accommodated to effect continuous recording and/or reproduction of the cassettes over a long period of time.
2. Description of the Prior Art
An automatic cassette changer for a television broadcasting station wherein a plurality of types of cassettes having different sizes are automatically exchanged to effect continuous reproduction, recording or edition of video signals over a long period of time has been proposed by the assignee of the present patent application and is disclosed, for example, in Japanese Patent Laid-Open Application No. 1-243265.
The automatic cassette changer is convenient in that cassettes of different sizes are selectively used in such a manner that a small cassette is used to televise a video signal for a comparatively short period of time such as a commercial, but a large cassette is used to televise a video signal for a comparatively long period of time such as a news program or other type of program.
This prior art automatic cassette changer, however, can handle only cassettes wherein the tapes thereof have a common recording format. Consequently, it is impossible to properly use a plurality of types of cassettes wherein the tapes have different recording formats such as tapes which have been recorded with different video cameras having different recording formats.
Also, an automatic cassette changer with a transport mechanism wherein a plurality of cassettes are successively exchanged to effect continuous reproduction, recording editing or the like over a long period of time has been proposed by the assignee of the present patent application and disclosed, for example, in Japanese Patent Application No. 3-156382.
The automatic cassette changer with a cassette transport mechanism includes two loading mechanisms including a main cassette loading mechanism and an auxiliary cassette loading mechanism, by means of which a cassette loading operation having a long stroke can be performed compactly.
With the automatic cassette changer which has a transport mechanism, however, the cassette loading mechanisms cannot be moved with respect to the transport mechanism in a direction perpendicular to the direction for inserting or removing a cassette, and the movement in the perpendicular direction can be achieved only by horizontal movement of the entire transport mechanism.
Accordingly, in the prior art automatic cassette changer, the entire transport mechanism must be moved in the vertical direction and the leftward and rightward horizontal direction, which makes the moving apparatus large. Thus, it is impossible to freely select the position for transferring a cassette in a direction perpendicular to the cassette inserting or removing direction with the transport mechanism simply being moved only in the vertical direction.
The automatic cassette changer disclosed in Japanese Patent Laid-Open Application No. 3-156382 is further constructed such that the transport mechanism includes a pair of upper and lower cassette holding pawls mounted for pivotal motion in the upward and downward directions such that a cassette is held in its thicknesswise direction by and between the cassette holding pawls to effect insertion or removal of the cassette into or from a cassette storage rack or the recording and reproducing apparatus.
With the automatic cassette changer, however, if the transport mechanism is displaced or offset in the vertical direction with respect to the cassette storage rack and the recording and reproducing apparatus, then, when a cassette is to be inserted from the transport mechanism into the cassette storage rack or the recording and reproducing apparatus, an end of the cassette may be abutted with and pinched in the cassette storage rack or the recording reproducing apparatus, each of which is quite rigid so that the cassette cannot be inserted farther than an intermediate position. On the other hand, when a cassette is to be removed from the cassette storage rack or the recording and/or reproducing apparatus there is a problem in that an end of the cassette may be pinched and stopped in the cassette storage rack of the recording/reproducing apparatus so that the cassette holding pawls to slip off the cassette, and consequently, the cassette cannot be withdrawn beyond an intermediate position.
Incidentally, in an automatic cassette changer of the type mentioned, a cassette which is discharged, for example, from the recording and reproducing apparatus does not always assume a correct position but instead assumes, in most cases, an inclined position within a horizontal plane with respect to the transport mechanism, due to the structure of the automatic cassette changer. Further, the relative distances between the transport mechanism and the cassette storage rack and the recording and reproducing apparatus, respectively, in the cassette inserting or removing direction are liable to present a considerable displacement.
With the automatic cassette changer disclosed in Japanese Patent Laid-Open Application No. 3-156382, however, when a cassette discharged, for example, from the recording and reproducing apparatus is to be held by and between the cassette holding pawls and taken into the transport mechanism, it is impossible to correct the inclination of the cassette with respect to the transport mechanism or to compensate for displacement between the cassette and the transport mechanism. Accordingly, there are difficulties in that the cassette is held in an unstable posture and in an inclined condition by and between the cassette holding pawls and the position at which the cassette is held by and between the cassette holding pawls is within such a narrow range that the cassette cannot be held with certainty.
Further, since this prior art automatic cassette changer cannot cope with cassettes having different thicknesses, it is difficult to provide an automatic cassette changer in which a plurality of types of cassettes having different thickness in accordance with different recording formats can be used.
Moreover, when a cassette is to be held from above and below between a pair of cassette holding pawls mounted for upward and downward pivotal motion as in the prior art automatic cassette changer, when it is desired to hold cassettes of varying thickness in accordance with diverse recording formats such as, for example, an 8 mm tape cassette and a digital tape cassette, one of the various types of cassette may not be held stably between the cassette holding pawls.
Accordingly, the prior art automatic cassette changer can handle only cassettes of uniform thickness, and it is difficult to provide an automatic cassette changer in which a plurality of cassettes having different thicknesses in accordance with diverse recording formats can be used to effect continuous video signal reproduction, recording, editing or the like over a long period of time.
A further automatic cassette changer has been proposed by the assignee of the present patent application and is disclosed in Japanese Patent Laid-Open Application No. 1-151448 wherein plurality of types of cassettes having different large and small sizes can be automatically exchanged to effect continuous video signal reproduction, recording, editing or the like over a long period of time.
This automatic cassette changer is convenient in that cassettes of different sizes are selectively used in such a manner that a small cassette is used to televise a video signal for comparatively short period of time such as a commercial, but a large cassette is used to televise a video signal for a comparatively long period of time such as a news program or other type of program.
This automatic cassette changer, however, can handle only cassettes wherein the tapes have a common recording format. Consequently, it is impossible to use a plurality of types of cassettes wherein the tapes have different recording formats such as tapes which have been recorded with difference video cameras having different recording formats.
In particular, one problem encountered with a automatic cassette changer that uses a plurality of types of cassettes having tapes of different recording formats and tape widths of 3/4 inches, 1/2 inch, 8 mm and so forth is that a cassette of the wrong type, such as a medium size cassette with 1/2 inch tape or a small cassette with 8 mm tape, may sometimes be inserted erroneously into a storage rack for large cassettes with 3/4 inch tape.
Another automatic cassette changer with a transport mechanism has been proposed by the assignee of the present patent application and is disclosed in Japanese Patent Application No. 3-204265 wherein a plurality of types of cassettes can automatically be exchanged to effect continuous video signal reproduction, recording, editing or the like over a long period of time.
This automatic cassette changer includes a transport mechanism that moves itself by means of a motor provided on the transport mechanism itself. The transport mechanism moves, in a vertical direction along a vertical rack provided on the body of the automatic cassette changer, and the entire automatic cassette changer is of a compact design.
With this automatic cassette changer, however, a pair of left and right travel guides for the transport mechanism are each formed by a fixed rail mounted on the automatic cassette changer body and extending in a direction perpendicular to the cassette inserting or removing direction, and a plurality of guide rollers are mounted on a transport mechanism and maintained in contact in the cassette inserting or removing direction with the fixed rail, and accordingly, it is difficult to restrict the movement or play of the transport mechanism in the leftward or rightward direction, that is, in a direction perpendicular to the cassette inserting or removing direction.
In order to restrict the movement of the transport mechanism in the leftward or rightward direction, an additional fixed rail extending in parallel to the cassette inserting and removing direction and a plurality of additional guide rollers normally held in contact with the additional fixed rail in a direction perpendicular to the cassette inserting or removing direction must be provided. This causes the overall size of the automatic cassette changer to be excessive, on account of the space occupied by the travel guides in the leftward and rightward directions, that is, in the direction perpendicular to the cassette inserting and removing direction, and also in the forward and backward directions, that is, in the cassette inserting and removing direction.
The prior art automatic cassette changer disclosed in Japanese Patent Laid-Open Application No. 243265 further has a disadvantage in that any cassette, whether of the large or small size, is positioned at the center of the transport mechanism by means of a cassette guide disposed in the transport mechanism, so that the position at which a cassette, for example, of the small size, is transferred to or from the cassette storage rack or the recording and reproducing apparatus cannot be selected freely in a direction perpendicular to the cassette inserting and removing direction.
Also the prior art automatic cassette changer disclosed in Japanese Patent Laid-Open Application No. 3-156382 has a further drawback in that it cannot handle a plurality of types of cassettes having different sizes.
The automatic cassette changer disclosed in Japanese Patent Laid-Open Application No. 3-156382 includes two loading mechanisms including a main cassette loading mechanism and an auxiliary cassette loading mechanism, by means of which a cassette loading operation having a long stroke can be performed.
With this type of automatic cassette changer, however, a cassette is transferred from or to the recording and reproducing apparatus by successive transferring operations of the two loading mechanisms, i.e. both of the main cassette loading mechanism and the auxiliary cassette loading mechanism. Consequently, a cassette cannot-be transferred from or to the recording and reproducing apparatus by operation only of the pair of upper ad lower cassette holding pawls constituting the main cassette loading mechanism.
Further, when a cassette is to be, for example, inserted into the recording and reproducing apparatus, it is impossible to push the cassette to a deep position at which a cassette insertion detecting switch provided at an interior position in the recording and reproducing apparatus is switched on, because the cassette is held in its thicknesswise direction between the upper and lower cassette holding pawls and there is a limit to the depth to which the cassette holding pawls can insert the cassette.
Particularly when the recording and reproducing apparatus is constructed so as to accept cassettes of the large and small sizes, in order to assure that a cassette of the large size is held securely by the cassette holding pawls, the cassette holding pawls must necessarily have a considerable length, but if the cassette holding pawls are too long, then the depth to which they can insert a cassette into the recording and reproducing apparatus is further restricted. Consequently, it is impossible to push a cassette of the small size in to an interior position in the recording and reproducing apparatus so that the front end face of the small size cassette may be positioned in registration with the position for a front end face of a cassette of the large size.